Odd idle issue with my SVO

[cobra_4]

So up until now, the SVO has ran pretty much flawlessly, but I haven't put a ton of miles on it either. In between working on it, I've been trying to log some miles between now and Mustang Week, rather than just head out on a six hour journey cold turkey. Sunday night it developed its first issue that I've noticed. Here's what happened.


I drove into town, probably five miles, pulled over and stopped about five minutes. When I headed back out, I noticed it felt like the car was surging a little or like I was on the gas when I wasn't. I was in a little bit of a high gear so I didn't think much of it. Then I pull up to the red light and it idles up to 2500 or so, then back down, then up, down, up down, not like a constant up and down, there was probably a three-five second interval between when it would idle up, then down. Took off from the light and could still feel it revving up while driving, but then at the next light it was fine. At the next light, I decided to video it(video below). Of course, an ambulance came by so you can't really here it, but you can see it revving up, then down, not as aggressive as before, then it just stops and goes back to normal. The high rev at the end was me trying to get it to act up again. Pulled out from the light, went home, it was fine.




So my question is, why or what caused it? Something to worry about? Im clueless when it comes to working on this four cylinder, if it was a V8 I'd think either the TPS or the idle air, but this is a new creature to me. If it doesn't do it again, I'd like to at least know what spare parts to throw in my emergency box, or go ahead and change them ahead of time.




Video link.

http://vid1249.photobucket.com/albums/hh513/JDSMotorsports/11111111/IMG_1423_zps5o7ykckl.mp4

[svono50]

Could be your idle air bypass valve or your TPS, either one could cause what you describe. Another potential cause could be an intermittent connection in one of the engine wire connectors. There should be 2 connectors along the firewall behind the intercooler. These two harnesses go to the intake control items. Pop them open and look at the female connector end and see if any of the connector tubes are opened up any, like the right hand one in the pic below. This turned out to be most of my 'odd' idle/part throttle issues.

Harness Wiring - Wedglock Pins_Female_TPS_01.jpg

[cobra_4]

Could be your idle air bypass valve or your TPS, either one could cause what you describe. Another potential cause could be an intermittent connection in one of the engine wire connectors. There should be 2 connectors along the firewall behind the intercooler. These two harnesses go to the intake control items. Pop them open and look at the female connector end and see if any of the connector tubes are opened up any, like the right hand one in the pic below. This turned out to be most of my 'odd' idle/part throttle issues.

[ATTACH=CONFIG]44360[/ATTACH]

Thanks for the input!! I'll check them out!

[cobra_4]

Is the idle air bypass valve something I can buy over the counter? I can't find a part number on it?

[SVOeric]

yeah, about every ford since 1984 has had one. there are several different configs (angled, straight, etc) they are fairly expensive new, but they are pretty cheap used, but sometimes what you get may be worse than what you already have.

[svono50]

I purchased mine from Rock Auto, it was a Standard Motor Products unit, model AC25...which doesn't seem to be listed any more. As Eric mentioned, they are pretty common on the 2.3L applications throughout the years, unfortunately the 'straight' connector style won't work with our intercoolers in the way, you will need a right-angle connector like the factory unit. A quick check on the 87-88 Turbocoupes shows a right-angle harness connector unit from Standard Motor Products, model AC29 and there is also an Airtex/Wells unit too, both right around $65-70. I feel I got mine for a steal 3 years ago for under $50 now.

[cobra_4]

I purchased mine from Rock Auto, it was a Standard Motor Products unit, model AC25...which doesn't seem to be listed any more. As Eric mentioned, they are pretty common on the 2.3L applications throughout the years, unfortunately the 'straight' connector style won't work with our intercoolers in the way, you will need a right-angle connector like the factory unit. A quick check on the 87-88 Turbocoupes shows a right-angle harness connector unit from Standard Motor Products, model AC29 and there is also an Airtex/Wells unit too, both right around $65-70. I feel I got mine for a steal 3 years ago for under $50 now.

Awesome thanks! I own a Carquest, so I should be able to work with that number, when I was clicking SVO, it was kicking that AC25 out, now I see why with the connector. Hopefully I can get an AC29 or an equivalent of it.

[cobra_4]

There was one AC29 left in the Carquest system nationwide, it's on its way to me from Michigan right now!!!

[svono50]

Good deal! Let us know how the connector angle works out, hopefully it is at a workable angle, as it appears to be ~45 deg off from the stock unit, which faces either straight forward or rearward depending on how you mount the solenoid.

[cobra_4]

Good deal! Let us know how the connector angle works out, hopefully it is at a workable angle, as it appears to be ~45 deg off from the stock unit, which faces either straight forward or rearward depending on how you mount the solenoid.

Will do!!

[SvoScott]

I had an 88 TC that had the same symptoms. I was lucky I have a good relationship with the dealership. They had it about a month working on it then testing. Changed about every part possible. What it turned out to be was a bad harness to the TFI on the side of the distributor.

I'm sure this is not a common problem but it fixed my tc